Attention recently h as been directed to implementing a variety of communication services, including voice telephone service, over the worldwide packet data network now commonly known as the Internet. The Internet had its genesis in U.S. Government programs funded by the Advanced Research Projects Agency (ARPA). That research made possible national internetworked data communication systems. This work resulted in the development of network standards as well as a set of conventions, known as protocols, for interconnecting data networks and routing information across the networks. These protocols are commonly referred to as TCP/IP. The TCP/IP protocols were originally developed for use only through ARPANET but have subsequently become widely used in the industry. TCP/IP is flexible and robust. TCP takes care of the integrity, and IP moves the data.
Internet provides two broad types of services: connectionless packet delivery service and reliable stream transport service. The Internet basically comprises several large computer networks joined together over high-speed data links ranging from ISDN to T1, T3, FDDI, SONET, SMDS, ATM, OT1, etc. The most prominent of these national nets are MILNET (Military Network), NSFNET (National Science Foundation NETwork), and CREN (Corporation for Research and Educational Networking). In 1995, the Government Accounting Office (GAO) reported that the Internet linked 59,000 networks, 2.2 million computers and 15 million users in 92 countries. However, since then it is estimated that the number of Internet users continues to double approximately annually.
In simplified fashion the Internet may be viewed as a series of packet data switches or `routers` connected together with computers connected to the routers. The Information Providers (IPs) constitute the end systems which collect and market the information through their own servers. Access providers are companies such as UUNET, PSI, MCI and SPRINT which transport the information. Such companies market the usage of their networks.
FIG. 3 shows a simplified diagram of the Internet and various types of systems which are typically connected. Generally speaking the Internet consists of Autonomous Systems (AS) type packet data networks which may be owned and operated by Internet Service Providers (ISPs) such as PSI, UUNET, MCI, SPRINT, etc. Three such AS/ISPs appear in FIG. 3 at 310, 312 and 314. The Autonomous Systems (ASs) are linked by Inter-AS Connections 311, 313 and 315. Information Providers (IPs) 316 and 318, such as America Online (AOL) and CompuServe, connect to the Internet via high speed lines 320 and 322, such as T1/T3 and the like. Information Providers generally do not have their own Internet based Autonomous Systems but have or use Dial-Up Networks such as SprintNet (X.25), DATAPAC and TYMNET.
By way of current illustration, MCI is both an ISP and an IP, SPRINT is an ISP, and the Microsoft Network (MSN) is an IP using UUNET as an ISP. Other information providers, such as universities, are indicated in exemplary fashion at 324 and are connected to the AS/ISPs via the same type connections here illustrated as T1 lines 326. Corporate Local Area Networks (LANs), such as those illustrated in 328 and 330, are connected through routers 332 and 334 and high speed data links such as T1 lines 336 and 338. Laptop computers 340 and 342 are representative of computers connected to the Internet via the public switched telephone network (PSTN), and are shown connected to the AS/ISPs via dial up links 344 and 346.
In the addressing scheme of the Internet, an address comprises four numbers separated by dots. This is called the Internet Protocol address, or IP address. An example of an IP address would be 164.109.211.237. Each machine on the Internet has a unique number assigned to it which constitutes one of these four numbers. In the IP address, the leftmost number has the greatest weight. By analogy this would correspond to the ZIP code in a mailing address. At times the first two numbers constitute this portion of the address indicating a network or a locale. That network is connected to the last router in the transport path. In differentiating between two computers in the same destination network only the last number field changes. In such an example the next number field 211 identifies the destination router.
When a packet bearing a destination address leaves the source router, the router examines the first two numbers in a matrix table to determine how many hops are the minimum to get to the destination. It then sends the packet to the next router as determined from that table, and the procedure is repeated. Each router has a database table that finds the information automatically. This continues until the packet arrives at the destination computer. The separate packets that constitute a message may not travel the same path depending on traffic load. However, they all reach the same destination and are assembled in their original order in a connectionless fashion. This is in contrast to connection oriented routing modes, such as frame relay and ATM or voice.
It would be difficult for most people to remember the four separate numbers (sometimes having ten or more digits) comprising each numeric IP address. In addition numeric IP addresses occasionally change, making it even more of a problem for people to keep track of them. The Domain Name System (DNS) was developed to provide some relief from these problems. In the DNS system words, which are more easily remembered, are used instead of numbers.
An example of a textual Domain Name is Evoit@HUT.MB.COM. Each of the names separated by a dot is called a domain. The significance of each of the domains is the reverse of that of the numeric IP address. In the numeric IP address, the most significant numbers were on the left and the least significant on the right. The textual Domain Name System begins with the least significant on the left and proceeds to the most significant on the right.
The top-level domains, those of the most general significance, are as follows:
1. COM A commercial operation PA1 2. EDU A university, college or other education institution PA1 3. GOV A government organization PA1 4. MIL A military site PA1 5. ORG Any organization that does not fit into any of the preceding PA1 6. NET A network PA1 1. Personal Computer (PC)--PC PA1 2. PC--Telephone PA1 3. Telephone--PC PA1 4. Telephone--Telephone
There are now two-letter domains, each denoting a different country, which are atop the above original domain names. An address ending in "COM.AU," for example, would be a commercial operation in Australia. Over a hundred different countries are now connected to the Internet so the list of two-letter country codes is ever increasing. Computers associated with the Internet called domain name servers convert textual domain names into numeric IP addresses.
Recently, one or more companies have developed software for use on personal computers to permit two-way transfer of real-time voice information via an Internet data link between two personal computers. In one of the directions, the sending computer converts voice signals from analog to digital format. The software facilitates data compression down to a rate compatible with modem communication via a POTS telephone line, in some cases as low as 2.4 kbits/s. The software also facilitates encapsulation of the digitized and compressed voice data into the TCP/IP protocol, with appropriate addressing to permit communication via the Internet. At the receiving end, the computer and software reverse the process to recover the analog voice information for presentation to the other party. Such programs permit telephone-like communication between Internet users registered with Internet Phone Servers.
Such programs have relied on servers coupled to the Internet to establish voice communication links through the networks. Each person active on the network, who is willing to accept a voice call, must register with a server. A calling party can call only those persons registered on the voice communication server. Also, the address management provided by these servers, like that provided by the domain name servers, has not permitted any individualized control of routing. For example, a user could register only one current address and must reregister each time the user comes on-line with a new address. The registration server provides no automatic selection of alternate destinations.
Concurrent with recent developments in public packet data communications such as the Internet, outlined above, the telephone industry has been developing an enhanced telephone network, sometimes referred to as an Advanced Intelligent Network (AIN), for providing a wide array of new voice grade telephone service features. In an AIN type system, local and/or toll offices of the public telephone network detect one of a number of call processing events identified as AIN "triggers". For ordinary telephone service calls, there would be not event to trigger AIN processing. The local and toll office switches would function normally and process such calls without referring to the central database for instructions. An office which detects a trigger will suspend call processing, compile a call data message and forward that message via a common channel interoffice signaling (CCIS) link to a database system, such as an Integrated Service Control Point (ISCP). Each ISCP includes a Multi-Services Application Platform (MSAP) database.
If needed, an ISCP can instruct the central office to obtain and forward additional information. Once sufficient information about the call has reached the ISCP, the ISCP accesses its stored data tables in the MSAP database. Using those tables it translates the received message data into a call control message and returns the call control message to the switching office of the network via CCIS link. The network switching offices then use the call control message to complete the particular call. An AIN type network for providing an Area Wide Centrex service, for example, was disclosed and described in detail in commonly assigned U.S. Pat. No. 5,247,571 to Kay et al., the disclosure of which is entirely incorporated herein by reference.
As shown by the art discussed above, the Internet and the AIN have remained separate, independent areas of technical development. Many telephone service subscribers are accustomed to enhanced telephone features, such as those provided by AIN processing. However, the wide range of conditional routing options offered by AIN type processing have not been available on the Internet. For example, the address processing provided by the domain name servers and the registration servers used to exchange addresses for voice communication have not permitted alternate treatments for different times, different calling parties, different destinations of roaming subscribers, etc. An enhanced domain name server which enables conditional routing and which is capable of wide database applications was disclosed and described in detail in the above-referenced parent Eric A. Voit U.S. application Ser. No. 08/812,075.
As use of the Internet expands, particularly for transport of voice telephone communications, a need exists not only for enhanced address management but also for distributed and scalable customer account authentication, authorization, usage recording, usage pricing billing account management, and inter carrier interfaces. The enhanced domain server described in the above incorporated Voit application Ser. No. 08/812,075 lends itself to serving in this capacity.
Voice over internetworks, and particularly the Internet (V/IP), involves terminal equipment affiliated with various networks. V/IP services can be divided into at least four categories based on the type of network to which the users' terminal equipment is attached, such as Internet/Intranet or narrowband Public Switched Telephone Network (PSTN) or POTS (plain old telephone service) telephone network. These four categories are:
Existing V/IP implementations over the Internet are subject to best-effort quality of service (QoS). Typically, this is noticeably degraded as compared to "toll quality" service. In addition, it is subject ot significant variations. There is a need for improvement over these existing implementations both in level and consistency of QoS. The QoS should be such as to be perceived by end users as consistently supporting comfortable conversation similar to that which users are accustomed. Preferably the QoS should be equivalent to "toll quality" voice service.
Residential and business customers on the PSTN are accustomed to the availability of enhanced calling features and it is desirable to provide personal dialing directories, ability to use multiple point to point connections at the same time, multi-line conferencing capabilities, and full duplex operation. Authorization and security features should be supplied, as well as user access to billing and usage accounting relating to their own accounts.
In addition to the foregoing developers of Internet telephony systems have encountered a variety of call set-up and routing issues in selection of the appropriate PSTN hop-off Internet Telephony Gateway (ITG) under a variety of ITG deployment scenarios.
While attempts are being made to develop an initial set of Internet Telephony Gateway (ITG) service architectures, to date no solution is presently known to exist to effectively cope with hop-off ITG selection when multiple ITGs are available for use. When multiple ITGs are available many factors bear upon the decision as to the most appropriate choice. These factors include:
Least Cost Routing
Which ITG selection will result in the lowest cost call for the customer (based on available tariff information).
Which ITG selection will result in the lowest cost rate for the carrier attempting to terminate the call for the customer (in essence, a carrier will be shopping for the highest margin between what the customer is paying the carrier, and what the carrier must pay to other carriers it involves in the call).
Which ITG selection will result in the shortest or least expensive packet switched network route for a carrier.
Which ITG selection will result in the shortest or least expensive circuit switched network route for a carrier.
Which ITG selection will result in the shortest or least expensive total combined circuit switched and packet switched network route for a carrier.
Resolving Geographical Boundaries
How to distribute calls between ITGs when several ITGs owned by different carriers serve the same hop-off calling area.
How to select the optimal ITG when several ITGs (which have different but overlapping calling areas) serve the same targeted called party.
Available PSTN Interface Resources
How to query for available (non-busy) ports across multiple Internet Telephony Gateway (ITG) systems. How to select the optimal ITG system based on responses from those systems.
How to reserve resources (via out of band signaling or otherwise) within an ITG and/or through an IP network, send the reservation to the user system which contacted the directory, and let the user system set-up a session with the ITG based on the reservation number.
Combinations of the Above Options
How to implement a decision matrix which helps to trade off issues regarding tariff rates, network efficiency in routing, quality of service of links, hop-off gateway carrier selection, and available ITG resources when selecting the "best" choice for a hop-off ITG.